DOS NOTES:

MS-DOS 4.01

Some of the external DOS commands can cause problems on the AMI
Enterprise motherboard with the older BIOS. The RAMDRIVE.SYS will cause
floppy access problems. See Tech Tip #11. DOS 3.3 and 5.00 RAMDRIVE
will not cause this problem.
EMM386 driver gives 'EMM386 Exception error' because DOS 4.01 does
not switch to real mode before giving control to the BIOS on reboot.
See Tech Tip 7. This problem does not exist in MS-DOS 5.

MS-DOS 5.0

'WARNING: Cannot disable Gate A20' is a common error. Basically,
the Gate A20 is an alternate method of controlling memory above 1Meg.
HIMEM.SYS is a memory manager that comes with DOS 5.00 which needs to
be able to actively control Gate A20. If for some reason this gate
cannot be disabled, the memory manager will not operate and the above
error message will be generated.
One problem that can occur is with the FAST GATE A20 option in the
Advanced CMOS Setup of AMI BIOS date 2/2/91 and later. This option is
a faster method of controlling the gate, but does not always work well
with the DOS 5.00 HIMEM.SYS. If the above error is displayed, reboot the
system, go into CMOS Setup, and disable the FAST GATE A20 option. The
error should go away. If the error persists, the system has a physical
problem with the Gate A20 logic. Part of this logic is contained in the
keyboard BIOS chip. The recommended course of action would be to change
this chip. If the error still occurs, consult the motherboard
manufacturer or distributor for repair instructions.

The following is a sample CONFIG.SYS file:

FILES=20
BUFFERS=20
STACKS=0,0
DEVICE=C:\HIMEM.SYS
DOS=HIGH,UMB
DEVICE=C:\DOS\EMM386.EXE RAM I=E000-EFFF
DEVICEHIGH=C:\MOUSE.SYS
DEVICE=C:\WINDOWS\SMARTDRV.SYS 2048 512

Lines 1, 2, and 3 are environment variables for the system.
More
information can be found on this in the DOS 5.00 user's manual.
Line 4 is the HIMEM.SYS memory manager. Some types of machines
require a switch on the end of this line for proper operation. Usually,
machine with AMI BIOS do not need such a switch and the HIMEM.SYS can be
used as above.
Line 5 loads the major portion of the operating system into upper
memory. This allows more free conventional memory for programs. The
letters UMB stand for Upper Memory Blocks.
Line 6 is the Expanded Memory Manager that comes with DOS 5.00. For
complete usage instruction consult the DOS 5.00 user's guide. The switch
I=E000-EFFF includes the E000 range of upper memory for use by the
system. A copy of System BIOS is made in this section on boot-up for use
by the setup or diagnostics. After boot, this section is released but
not erased, so it appears to have a ROM residing there.
Line 7 is an example of how to load device drivers into high memory
in the CONFIG.SYS file.
Line 8 is the Smartdrive diskcache software that comes with Windows.
The switches appended to the command line set up a maximum 2Meg cache
and a minimum 512K cache.